Energy- and Emissions-Intensive Industries
- Low Carbon Fuels and Feedstocks
- Thermal Processes and Systems
Low carbon fuels and feedstocks represent a key opportunity to increasing energy efficiency in the industrial sector. Fossil fuels such as coal, oil, and natural gas are energy-dense – they store a lot of energy per unit of volume or mass. Industry uses fossil fuels to convert easily stored energy into heat, power, or electricity through combustion, on demand, releasing CO2 and other greenhouse gases as a byproduct.
Low- and zero-carbon fuels can be used as alternatives. Turbines designed for natural gas combustion can use hydrogen instead, avoiding CO2 emissions. Hydrogen can also be reacted with captured CO2 to produce energy-dense liquid fuels. Biofuels, produced from carbon captured from the air, can reduce the overall carbon content of the industrial fuel.
Overall, production of feedstocks accounts for about 1/10 of global fossil fuel usage. Feedstocks are materials used directly in manufacturing processes. The chemicals industry, for example uses natural gas to synthesize feedstocks in industries from plastics to fertilizer production.
Ammonia (NH4), used as a feedstock in fertilizers, is synthesized by extracting hydrogen from methane (CH4) and combining it with nitrogen (N), generating CO2 from the methane. Although chemical manufacturers re-capture much of the excess CO2 for use in other industrial processes, ammonia production alone accounts for about 1% of global carbon emissions.
A zero-carbon alternative for feedstocks would be to derive hydrogen from a source that doesn’t contain carbon – for example, water (H2O). Hydrogen gas can be converted from water through electrolysis – a process that requires electricity and zero carbon inputs.
Other important feedstocks include precursors for plastics and other materials, such as propylene and ethylene. Conventionally, these are produced from refining of petroleum and natural gas liquids, which produces these molecules in high temperature reactors. Since these feedstocks consist of both carbon and hydrogen, decarbonizing production of these feedstocks can’t be accomplished solely by sourcing zero-carbon hydrogen. Energy savings and carbon reduction opportunities can be found by electrifying this process or by finding chemical routes that do not emit greenhouse gases, like by directly using CO2 as a source of carbon.